For many applications sealing devices are required which seal a first side of a machine part against a second side of it. E. g. an oil side (first side) has to be sealed against an air side (second side) at a shaft of a combustion engine. Also, in many cases a bearing arrangement has to be sealed which is done by sealing devices of the kind mentioned above. Such sealing devices and their sealing elements are under high load as often they have to be pressed against their counter element by biasing means, e.g. springs, to ensure tightness of the sealing arrangement. Therefore, attempts have been made to strengthen the durability of the sealing elements. This applies especially if lubrication conditions are poor.
For metal parts different methods for applying coatings are known. Most of them are not applicable for sealing elements which consists normally of rubber material, elastomer material and especially polytetraflourethylene (PTFE).
For example U.S. Pat. No. 6,340,245 B1 describes a roller bearing having an inner ring, an outer ring and rolling elements which are in rolling contact with the raceways of the rings. The rolling elements as well as the raceways of the rings are coated with a metal-mixed diamond-like carbon layer. Especially, the respective elements are coated with a metal-mixed diamond-like carbon coating comprising alternating layers of predominantly diamond-like carbon, but containing some metal carbide, and layers of predominantly metal carbide, but containing some of the diamond-like carbon.